Question

我有一个表格，其中所有数据都按行存储。

key      name   field   value
11       sam    state   1
11       fred   state   1
21       sam    state   3
21       fred   state   1
11       sam    dist    1
11       fred   dist    1
21       sam    dist    1
21       fred   dist    1

我需要一个查询来获取"name" having dist = 1 with state = 1的数量。

以下内容...... 选择计数（值）从表 where field ='dist' 和值= 1 和键，名称（从表中选择键，名称，其中field ='state'和value = 1）

在上面的示例中，我希望答案为“3”（带键= 21的山姆不符合条件）。

Answer 1

试试这个：

select count (value) 
from table a
where  field = 'dist' 
and value = 1 
and exists
(
  select 1 from table n where field = 'state' and value =1
  and a.key = b.key 
  and a.name = b.name
)

Answer 2

select count(distinct yourtable.name)
from yourtable
inner join
(
    select key, name from yourtable
    where field='dist' and value = 1
) dist1
    on yourtable.key = dist1.key 
    and yourtable.name = dist1.name
where field='state' and value = 1

Answer 3

使用联接：

select count(distinct key, name) from table t1
inner join table t2
  on t2.key = t1.key and t2.name = t1.name and t2.field = 'state' and t2.value = 1
where t1.field = 'dist' and t1.value = 1

“IN”子句中的多个内联变量

3 个答案: